A snorkel is one major device being used by a skin diver in snorkel diving, so that the diver can keep breathing while enjoying underwater scenery.
Please refer to FIG. 1. Generally, a diving snorkel includes a snorkel tube 500 having an upper open end and a lower end having a mouthpiece 510 connected thereto. Air from above water surface can be supplied via the snorkel tube 500 to the diver's mouth for breathing. Air exhaled by the diver can also be exhausted via the snorkel tube 500.
There are chances sea water would invade into the snorkel tube 500 via the upper open end thereof when the diving depth is larger than the length of the snorkel tube 500 or when sea water splashes on the snorkel tube 500, causing the diver to inhale water while taking breath. To avoid such condition, a water stopper is usually mounted to the upper open end of the snorkel tube 500 to automatically close the upper open end when the latter is lower than the water surface, preventing sea water from undesirably entering the snorkel tube 500.
FIG. 1 is a schematic view of a diving snorkel with a conventional water stopper 600 mounted thereto being shown in a sectional view; FIG. 2 is an enlarged sectional view of the conventional water stopper 600 shown in FIG. 1; and FIG. 3 is a cross sectional view taken along line A-A of FIG. 2. As shown, the conventional water stopper 600 includes a sleeve 610 connected to an upper end of a snorkel tube 500 and having a plurality of air valve openings 611 spaced on a diametrically expanded upper end thereof, a ring-shaped housing 620 connected to the upper end of the snorkel tube 500 to locate around the sleeve 610 and having a plurality of air intakes 621 formed thereon, an annular float 630 disposed between the sleeve 610 and the ring-shaped housing 620 to normally locate below the air valve openings 611, and a cap 640 closed onto a top of the ring-shaped housing 620.
When the snorkel tube 500 is used under normal condition, the water stopper 600 is located above the water surface 700 and the annular float 630, due to its own weight, is located at a descended position between the sleeve 610 and the ring-shaped housing 620 to thereby open the air valve openings 611. At this point, air from above water surface can sequentially flow through the air intakes 621, the air valve openings 611, the sleeve 610, and the snorkel tube 500 to the diver's mouth for breathing.
However, when the water surface 700 is higher than the upper end of the snorkel tube 500, sea water will first contact with a bottom of the annular float 630. At this point, the annular float 630 ascends between the sleeve 610 and the ring-shaped housing 620 due to a buoyancy of water to finally close the air valve openings 611. With the closed air valve openings 611, sea water is prevented from invading into the snorkel tube 500 via the air valve openings 611 and the diver is protected from inhaling water.
Meanwhile, the closed air valve openings 611 also prevent the diver from breathing air from above the water surface. The diver is therefore informed that the water surface has already contacted with the bottom of the annular float 630 and the snorkel tube 500 must be adjusted to a different angle to expose from the water surface or the diving depth must be reduced, so that the annular float 630 is located above the water surface and can therefore descend between the sleeve 610 and the ring-shaped housing 620 to open the air valve openings 611 again, allowing the diver to breathe air from above the water surface.
Please refer to FIG. 2. As a matter of fact, the snorkel tube 500 is usually not always in a fully vertical state but will tilt in different directions along with the diver's head when the diver moves about underwater to see surrounding scenery.
According to the conventional water stopper 600, the annular float 630 serving to control the open and close of the air valve openings 611 is an integrally formed one-piece float unit. Whenever the snorkel tube 500 in use is tilted to cause any side of the bottom of the annular float 630 to contact with the water surface 700, the whole annular float 630 would immediately ascend due to the buoyancy of water to thereby close all the air valve openings 611, as shown in FIGS. 2 and 3. As a result, the diver must immediately adjust the inclination angle of the snorkel tube 500 or reduce the diving depth, lest the annular float 630 should keep closing the air valve openings 611.
As having been mentioned above, the snorkel tube 500 in use is usually frequently in a tilted position. Therefore, when one side of the bottom of the annular float 630 contacts with the water surface 700, an opposing side of the bottom of the annular float 630 might still be higher than the water surface 700. The diver would not have to immediately adjust the inclination angle of the snorkel tube 500 or reduce the diving depth if the air valve openings 630 closer to the opposing side of the annular float 630 above the water surface 700 are kept open to let in external air to the snorkel tube 500 for breathing. However, with the integrally formed one-piece annular float 630 for the conventional water stopper 600, all the air valve openings 611 are closed simultaneously when any part of the bottom of the annular float 630 is in contact with the water surface 700 because the one-piece annular float 630 always ascends as a whole between the sleeve 610 and the ring-shaped housing 620. Therefore, with the conventional water stopper 600, the diver has to frequently adjust the inclination angle of the snorkel tube 500 or reduce the diving depth in response to the water-contacting annular float 630. This is of course inconvenient for the diver to do so.
Furthermore, according to the conventional water stopper 600, the cap 640 is closed onto the top of the ring-shaped housing 620 without shielding the air intakes 621 on the ring-shaped housing 620 from splashing waves. Therefore, splashing waves tend to invade into the snorkel tube 500 via the unshielded air intakes 621, causing the diver to unexpectedly inhale water while taking breath.